

.itemBox {
  width: 430px;
  height: 135px;
  position: relative;
}
.itemBox img {
  max-width: 100%;
  max-height: 100%;
  display: block;   /* 重点 */
  margin: auto;
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
}